As will be appreciated herein below, except as otherwise indicated, alloy designations and temper designations refer to the Aluminum Association designations in Aluminum Standards and Data and the Registration Records, as published by the Aluminum Association.
For any description of alloy compositions or preferred alloy compositions, all references to percentages are by weight percent unless otherwise indicated.
Because of their light weight, aluminum alloys have found wide use in military applications, including military vehicles such as personnel carriers. The light weight of aluminum allows for improved performance and ease of transporting equipment, including air transport of military vehicles. In some vehicles it is advisable to provide shielding or protection against assault, by providing armour plate to protect the occupants of the vehicle. Aluminum has enjoyed substantial use as armour plate, and there are a number of armour plate specifications for the use of different aluminum alloys.
The most relevant requirements for aluminum alloy armour plate are resistance to projectiles, good corrosion resistance, and in some applications, good weldability. Ballistic tests are often conducted with armour piercing (“AP”) projectiles such as the 7.62 mm AP M2 and with fragment simulating projectiles (“FSP”) such as the common 20 mm projectile. Aluminum alloys which satisfy all the requirements for armour plate are desirable, and these desires have been met to varying degrees. Aluminum alloys AA5083 and AA5456 are covered in the U.S. Military Specification for armour plate MIL-DTL-46027J (September 1998), and the alloy AA7039 is covered in the U.S. Military Specification MIL-DTL-46063H (September 1998). It is generally recognized that for many applications the alloy AA7039 armour plate is better than AA5083 and AA5456 armour plate, although the advantage is more for armour piercing ballistic performance and less so for fragment simulation performance, at least according to the military specifications. However, the alloy AA7039 can present corrosion or stress corrosion problems to a much greater degree than AA5083 and AA5456. The alloy AA7039 is very difficult to weld. The AA7039 alloy when used for armour plate applications is commonly in a T6 temper and the AA5083 and AA5456 alloys when used for armour plate applications is used in the H131 temper.
The compositional ranges for AA5083 are, in weight percent:                Mg 4.0-4.9        Mn 0.40-1.0        Cr 0.05-0.25        Si max. 0.40        Fe max. 0.40        Cu max. 0.10        Zn max. 0.25        Ti max. 0.15        impurities each element <0.05, total <0.15,        balance aluminum.        
The nominal composition for the AA5083 alloy is about 4.4 wt. % Mg, 0.7 wt. % Mn and 0.15 wt. % Cr.
The compositional ranges for AA5456 are, in weight percent:                Mg 4.7-5.5        Mn 0.50-1.0        Cr 0.05-0.20        Si max. 0.25        Fe max. 0.40        Cu max. 0.10        Zn max. 0.25        Ti max. 0.20        impurities each element <0.05, total <0.15,        balance aluminum.        
The nominal composition for the AA5456 alloy is about 5.0 wt. % Mg, 0.7 wt. % Mn and 0.15 wt. % Cr.
The compositional ranges for AA7039 are, in weight percent:                Zn 3.5-4.5        Mg 2.3-3.3        Mn 0.10-0.40        Cr 0.15-0.25        Si max. 0.30        Fe max. 0.40        Cu max. 0.10        Ti max. 0.10        impurities each element <0.05, total <0.15,        balance aluminum.        
The nominal composition for the AA7039 alloy is about 4 wt. % Zn, 2.8 wt. % Mg, 0.25 wt. % Mn and 0.20 wt. % Cr.
Unless otherwise indicated, all composition percents in the present specification are weight percents.
The most important requirements for aluminum alloy armour plate are resistance to projectiles, good corrosion resistance and stress corrosion resistance in particular, and in modern applications, good weldability. Ballistic tests are often conducted with armour-piercing projectiles such as 0.30 inch calibre projectiles and with fragment-simulating projectiles such as the common 20 mm projectile. Aluminum alloys which satisfy all the requirements for armour plate are desirable.
Another aluminum-magnesium alloy is the AA5059 alloy registered with the Aluminum Association in June 1999. The registered compositional ranges for AA5059 are, in weight percent:                Mg 5.0-6.0        Mn 0.6-1.2        Zn 0.40-0.9        Zr 0.05-0.25        Cr max. 0.25        Si max. 0.45        Fe max. 0.50        Cu max. 0.25        Ti max. 0.20        impurities each element <0.05, total <0.15,        balance aluminum.        
This aluminum alloy is also disclosed in U.S. Pat. No. 6,238,495-B2 and U.S. Pat. No. 6,342,113-B2, both incorporated herein by reference in their entireties. The aluminum alloy is for the construction of large welded structures such as storage containers and vessels for marine and land transportation. The alloy has found in particular commercial usage in shipbuilding application, whereby the aluminum alloy is typically in the H321-temper or 0-temper and has a thickness or gauge of less than 20 mm. According to U.S. Pat. No. 6,238,495 the H321 temper was reached by a cold rolling reduction of 40% followed by heat treating by soaking the cold rolled product at 250° C. for one hour. The 0-temper was reached by a cold rolling reduction of 40% followed by soaking to cold rolled product at 525° C. for a period of 15 minutes.